RNAlater® Tissue Collection: RNA Stabilization Solution is an aqueous storage reagent that protects RNA within intact, unfrozen tissues and cells, so samples do not need to be processed immediately after harvesting. This is important for large-scale experiments like the Toxicogenomics Project, which seeks to forecast the safety of candidate compounds during early drug development. A comparison of different tissue storage methods led Dr. Kasahara, et al. (National Institute of Biomedical Innovation, Osaka, Japan) to recommend RNAlater®Solution as one way to preserve tissues for gene profiling [1].

AM7020

Toxicogenomics Project

The Toxicogenomics Project is a collaboration among the Japanese National Institute of Health Sciences, the Japanese National Institute of Biomedical Innovation, and several pharmaceutical companies. After rats were treated with ~150 substances, toxicological measures (e.g., body/organ weight, blood biochemistry, and histopathology) and gene expression profiles of liver samples were obtained. The results will be used to help predict toxicity of new chemicals during early drug development.

Analysis of Sample Storage Methods

Because the quality of RNA greatly influences the accuracy of gene expression data, sample storage conditions are crucial. Methods for preserving RNA for transcriptome analysis were evaluated for the Toxicogenomics Project [1]. The experiments examined preservation of RNA samples stored in RNAlater Solution (1 day to 12 months), compared with tissues snap-frozen in liquid nitrogen or dissolved in a cell lysis buffer. The effects of repeated freezing/thawing on RNA quality were also evaluated. RNA degradation and purity were assessed by total yield, A260/A280 ratio, 28S/18S rRNA ratio, and beta-actin quantity.

Results and Recommendations

The samples dissolved in cell lysis buffer and stored at –20ºC showed degradation, but samples stored at –80ºC were almost equivalent to tissues stored in liquid nitrogen. RNAlater Solution maintained the quality of RNA: no change was noticed in the total RNA yield or A260/A280 ratio of the samples. Therefore, RNAlater Solution can be used to stabilize unfrozen samples for up to 2 weeks, while frozen samples kept below –20ºC are stable for at least one year.